Money or assets put to economic use, the life-blood of capitalism. Economists describe capital as one of the four essential ingredients of economic activity, the factors of production, along with land, labour and enterprise. Production processes that use a lot of capital relative to labour are capital intensive; those that use comparatively little capital are labour intensive. Capital takes different forms. A firm's assets are known as its capital, which may include fixed capital (machinery, buildings, and so on) and working capital (stocks of raw materials and part-finished products, as well as money, that are used up quickly in the production process). Financial capital includes money, bonds and shares. Human capital is the economic wealth or potential contained in a person, some of it endowed at birth, the rest the product of training and education, if only in the university of life. The invisible glue of relationships and institutions that holds an economy together is its social capital.